Method and apparatus for calibrating an endoscope system

ABSTRACT

An endoscope system and method includes an endoscope tip coupled to a endoscope console for providing images of anatomical features imaged using the endoscope system. The system also includes a calibration device having known optical properties. The calibration device is imaged using the endoscope system, and data corresponding to the image is obtained. This data are compared to data corresponding to the known optical properties of the calibration device. Based on this comparison, calibration data corresponding to imaging errors of the endoscope system are obtained. The calibration data are used to calibrate the endoscope system.

TECHNICAL FIELD

This invention relates to endoscope systems, and, more particularly, toinsuring that endoscope images accurately show anatomical featuresimaged with endoscope systems.

BACKGROUND

Endoscope systems have been in general use for many years fornon-invasively viewing anatomical features such as tissues and organsinside the human body. Endoscope systems typically include an endoscopetip having a flexible or rigid insertion tube having a headpiece mountedat its proximal end and a viewing window at its distal end. Theheadpiece of an endoscope tip having a flexible insertion tube normallyincludes controls, such as wheels or levers, connected to the distal endof the insertion tube by control wires to steer the end of the insertiontube in different directions. By manipulating the controls, anendoscopist can direct the viewing window at the distal end of theinsertion tube over a wide range of directions to view tissues andorgans located adjacent the distal end of the endoscope tip. Theinsertion tube also normally includes an illumination device fordirecting light into the body in the vicinity of the distal end of theinsertion tube. The illumination device is typically an optical fiberextending from a light source at the proximal end of the insertion tubeto an illumination window at the distal end of the insertion tube.However, the illumination may also be a light source mounted at thedistal end of the insertion tube and powered with electricity coupledthrough wires extending through the insertion tube. Endoscope tips alsoinclude a viewing device to allow the endoscopist to view anatomicalfeatures, such as tissues and organs, through the viewing window.

Endoscope systems may be used to simply view anatomical features, orthey may be used to non-invasively conduct various diagnostic orsurgical procedures within the body. Endoscope tips used for thispurpose often include a biopsy channel extending through the insertiontube from an access port at the proximal end of the insertion tube to anopening at the distal end of the insertion tube. Biopsy and surgicalinstruments attached to the distal end of catheters may be fed throughthe biopsy channel of the endoscope tip and out the biopsy channelopening to position the instruments adjacent the viewing window of theendoscope tip. A biopsy or surgical procedure can then be performed bysuch techniques as manipulating the endoscope tip controls, advancing orretracting the endoscope tip within the body, advancing or retractingthe catheter within the biopsy channel, or manipulating an actuator thatis mechanically coupled to the biopsy or surgical instrument. Endoscopetips that do not have biopsy channels can also be used to perform biopsyor surgical procedures. In such cases, one or more biopsy or surgicalinstruments are introduced into the body by suitable means, such as byusing a laparoscopic catheter. The biopsy or surgical instruments arethen positioned within the field of view of the endoscope tip viewingwindow.

To improve performance, specialized endoscope tips have been developedto best accomplish their intended function. For example, upper endoscopetips are used for examination of the esophagus, stomach and duodenum,colonoscopes are used for examining the colon, angioscopes are used forexamining blood vessels, bronchoscopes are used for examining thebronchi, laparoscopes are used for examining the peritoneal cavity, andarthroscopes are used for examining joint spaces. Instruments to examinethe rectum and sigmoid colon, known as flexible sigmoidoscopes, havealso been developed. The discussion of endoscope tips herein generallyapplies to these and other types of endoscope tips, and the term“endoscope tip” as used herein is meant to encompass all these and othersuch devices.

As mentioned above, endoscope tips include some form of viewing devicefor allowing anatomical features to be viewed through viewing windows.One type of viewing device uses a fiber-optic bundle extending from theviewing window at the distal end of the insertion tube to a viewingwindow on the headpiece. The fiber-optic bundle optically couples imagesthroughout the length of the insertion tube. Another type of viewingdevice uses a miniature video camera positioned behind the viewingwindow at the distal end of the insertion tube. Wires extending from thevideo camera through the insertion tube couple power to the camera andvideo signals from the camera. Still another type of viewing devicesuses a beam scanning device positioned behind the viewing window. Suchscanned beam endoscope tips are a fairly recent innovation.

Regardless of which type of viewing device is used by an endoscopesystem, the image obtained by using the endoscope system may notaccurately show the size, shape, color or other property of theanatomical features being viewed with the endoscope system. For example,it may be difficult to accurately asses the size of an internal object,such as a tumor, using any of the above-mentioned endoscope types. Itmay also be difficult to accurately show the true color of tissues ororgans. For endoscope tips using optical fibers to view an image, thebrightness of the image may be affected by light attenuation in theoptical fiber. The color of the image obtained using an endoscope systemmay be affected, for example, by the spectral properties of theilluminating light or the spectral transfer properties of the opticalfiber or video camera. Endoscope tips using cameras and beam scannerssuffer from additional problems not encountered in endoscope tips usingan fiber-optic bundle, such as the true contrast or sharpness of anendoscopically obtained image. And even endoscope tips using afiber-optic bundle will suffer from these limitations if images obtainedusing the endoscope system are converted to digital form.

There is therefore a need for an image calibration apparatus and methodthat allows an endoscope system to be calibrated so that it canaccurately portray anatomical features.

SUMMARY

A endoscope method and system allows an endoscope system to obtainimages that accurately portray anatomical features being imaged by theendoscope system. The endoscope system includes an endoscope tip that ispositioned so that the internal anatomical features are within a fieldof view of the endoscope tip, and an image of the internal anatomicalfeatures are obtained. Either before or after the image of the internalanatomical features are obtained, a calibrating device having at leastone known optical property is placed in the field of view of theendoscope tip, and an image of the calibrating device is obtained usingthe endoscope system. Calibration device data corresponding to the atleast one known optical property of the calibration device is used withthe image of the calibration device to provide calibration data. Thecalibration data is used to program the endoscope system and method toensure that the endoscopically obtained image accurately portrays theimaged internal anatomical features.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is schematic isometric view of an endoscope system that can beused with a calibration device according to one example of theinvention.

FIG. 2 is schematic cross-sectional view of the distal end of one typeof an endoscope insertion tube that can be used with a calibrationdevice according to an example of the invention.

FIG. 3 is schematic cross-sectional view of the distal end of anothertype of an endoscope insertion tube that can be used with a calibrationdevice according to an example of the invention.

FIG. 4 is schematic cross-sectional view of the distal end of stillanother type of an endoscope insertion tube that can be used with acalibration device according to an example of the invention.

FIG. 5 is an isometric view showing a calibration device according toone example of the invention in use with an endoscope system.

FIG. 6 is a flowchart showing one method for using a calibration deviceaccording to one example of the invention.

FIG. 7 is an isometric view showing a calibration device according toanother example of the invention.

FIG. 8 is an isometric view showing a calibration device according tostill another example of the invention that can be inserted into thebiopsy channel of an endoscope tip.

DETAILED DESCRIPTION OF THE EMBODIMENTS

An endoscope system 10 that can be used with calibration devicesaccording to various examples of the invention is shown in FIG. 1. Theendoscope system 10 includes an endoscope tip 100 having a flexibleinsertion tube 102 extending from a headpiece 108. As is well known inthe art, the insertion tube 102 includes a viewing device for conveyingan image from a distal end 104 to a proximal end 106 of the insertiontube 102, which is attached to the headpiece 108. A number of differentviewing devices can be used. For example, the distal end 104 of theinsertion tube 102 may contain a lens positioned behind a viewing window110 that is optically coupled to the headpiece 108 through a fiber-opticbundle (not shown in FIG. 1). The fiber-optic bundle can extend to aneyepiece (not shown in FIG. 1) projecting from the headpiece 108 thatcan be fitted with an optical-electrical converter (not shown) totransform the optical image into corresponding electrical signals.However, in the endoscope system 10 shown in FIG. 1, the viewing deviceis an imager 116, such as a miniature video camera, a scanned beamimager, or other imaging device, mounted at the distal end 104 of theinsertion tube 102. The imager 116 is electrically coupled to a console120 by electrical wires 124 extending from the imager 116 to theheadpiece 108 through the insertion tube 102 and then to the console120. The console 120 includes a viewing monitor 126 on which anendoscopic image may be viewed, and controls 128 for adjusting the imageshown in the monitor 126.

Regardless of which viewing device is used, the endoscope insertion tube102 may also include an illumination device (not shown in FIG. 1) forilluminating anatomical features to be viewed with the endoscope system10. These structures can take the form of, for example, a light sourcemounted at the distal end 104 of the insertion tube 102, with the lightsource being powered through wires extending from the headpiece 108through the insertion tube 102. Alternatively, a fiber-optic bundle canbe connected to a light source (not shown) and coupled to the headpiece108 via a fiber-optic bundle (not shown). This illuminating fiber-opticbundle is coupled to another fiber-optic bundle (not shown) that extendsthrough the insertion tube 102 to its distal end 104. In either case,light may be directed from the distal end 104 of the insertion tube 102to the anatomical features that are to be imaged. The spectralproperties of the light from the light source may affect the accuracy ofwhich the colors in an endoscopic image are portrayed.

If the endoscope tip 100 has a flexible insertion tube, such as theendoscope tip 100 shown in FIG. 1, the insertion tube 102 may alsocontain control cables (not shown) symmetrically positioned within theinsertion tube 102. As explained above, such control cables move thedistal end 104 of the insertion tube 102 in two orthogonal axes to steerthe endoscope tip's field of view. The control cables are anchored nearthe distal end 104 of the insertion tube 102, and they extend along thelength of the insertion tube 102 to knobs 130. In use, the knobs 130 arerotated to retract and extend oppositely positioned control cables.

Although not required for imaging anatomical features, the endoscope tip100 may also include auxiliary tubes or channels extending from theheadpieces 108 to the distal end 104 of the insertion tube 102 forperforming a variety of functions. One of these tubes is a wash channel(not shown) by which pressurized water can be injected through a nozzle(not shown) at the distal end 104 of the insertion tube 102 to clean thelens 108. Another channel (not shown) is used to instill air or CO₂ gasto distend the hollow organ and permit visual inspection. These channelsare selectively opened by actuating respective trumpet valves 134projecting from the headpiece 108. Regardless of whether or not anendoscope tip has these channels, it can be used with variouscalibration devices in accordance with the invention to ensure that anendoscopic image accurately portrays imaged anatomical features.

The endoscope tip 100 may also include a biopsy channel (not shown inFIG. 1) extending from an access port 140 to an opening 144 at thedistal end 104 of the insertion tube 102. The biopsy channel is normallyused to pass various biopsy and other devices (not shown in FIG. 1),both diagnostic and therapeutic, to the distal end 104 of the insertiontube 102 to perform specific functions. As explained in greater detailbelow, the biopsy channel can be used to pass to calibration devicesaccording to various examples of the invention to the field of view ofthe endoscope tip 100 in order to calibrate the endoscope system 10.

As mentioned above, a variety of endoscope tips may be used with theimage calibration system and method according to various examples of theinvention. One such endoscope tip 150 shown in FIG. 2 couples an imagethrough an optical fiber 160 extending from a distal end 164 of aninsertion tube 166. The optical fiber 160 extends to anoptical-electrical converter (not shown in FIG. 2), which may be mountedin the headpiece 108 (FIG. 1). The optical-electrical convertertransforms the optical image into corresponding electrical signals,which are coupled to the console 120 through the wires 124.

The endoscope tip 150 also includes a second fiber-optic bundle 168through which light is coupled to illuminate the field of view of theendoscope tip 150. A biopsy channel 170 also extends through theinsertion tube 166 to an opening 174 at the distal end 164 of theinsertion tube 166. As explained in greater detail below, a calibrationdevice (not shown in FIG. 2) is attached to the distal end of a catheter(not shown in FIG. 2) to position the calibration device adjacent thefiber-optic bundle 160 so it can be viewed through the endoscope tip150.

A portion of another endoscope tip 180 that can be used with the imagecalibration system and method according to various examples of theinvention is shown in FIG. 3. The endoscope tip 180 includes a miniaturevideo camera 184 of conventional design mounted in a distal end 186 ofan insertion tube 190 behind a viewing window 194. Wires 196 extend fromthe video camera 184 through the insertion tube 190 to the headpiece 108(FIG. 1) and to the console 120, as described above. The endoscope tip180 also includes a fiber-optic bundle 198 that couples illuminationlight to the field of view of the endoscope tip 180. Unlike theendoscope tip 150 shown in FIG. 2, the endoscope tip 180 does notinclude a biopsy channel through which calibration devices may bepassed. Therefore, as explained further below, the calibration devicesare introduced into the field of view of the endoscope tip 180 througheither the same body orifice or incision through which the endoscope tip180 is inserted or through a different orifice or incision.

Still another example of an endoscope tip 200 that can be used with animage calibration system and method according to various examples of theinvention is shown in FIG. 4. The endoscope tip 200 includes aninsertion tube 202 having a distal end 206 containing a scanning module210. The scanning module 210 includes a micro-electro-mechanical (MEMS)scanner 214 and associated components, and an illumination optical fiber218 mounted in the insertion tube 202 by a ferrule 220. The endoscopetip 200 also includes a beam shaping optical element 224 and atransparent dome 228 affixed to the distal end 206 of the insertion tube202, which may be hermetically sealed to protect the scanning module210.

In operation with the calibration system and method, the distal end 206of the insertion tube 202 is inserted into a body cavity. Theillumination optical fiber 218 transmits a beam 230 to the scanningmodule 210 and is shaped by the beam shaping optical element 224 to forma selected beam shape. After shaping, a shaped beam 234 is transmittedthrough an aperture in the center of the MEMS scanner 214, reflected offa first reflecting surface 238 of the interior of the dome 228 to thefront of the scanner 214, and then reflected off of the scanner 214 andthrough the dome 228 to provide a scanning beam 240. The scanning beam240 is scanned across a field-of-view (FOV) and reflected off of theinterior of a body cavity. At least a portion of the reflected lightfrom the FOV (e.g., specular reflected light and diffuse reflected lightalso referred to as scattered light) is collected by the detectionoptical fibers 218. The reflected light collected by the detectionoptical fibers 218 may be converted to an electrical signal by anoptical-electrical converter 260, which may be a set of photodiodes. Theconverter 260 outputs a signal that is converted to image data bycircuitry in the console 120 (FIG. 1). The image data is used togenerate an image that may be viewed on the monitor 126 of the console120.

According to one example of the invention, the endoscope tip 200 may becalibrated in the same manner as the endoscope tip 180 of FIG. 3 byplacing a calibration device (not shown) having at least one knownoptical property in the field of view of the endoscope tip 200.Electronic circuitry in the console 120 uses the image of thecalibration device to obtain calibration data. This calibration datathat is used to ensure that images of anatomical features obtained usingthe endoscope tip 200 accurately portray the anatomical features.

A calibration device 300 according to one example of the invention isshown in FIG. 5. The calibration device 300 is in the form of a label304 attached to a laparoscopic instrument 306, although it mayalternatively be attached to other devices that are inserted eitherthrough a biopsy channel of an endoscope tip, an orifice or incisionthrough which the endoscope tip is inserted, or some other orifice orincision. Calibration targets 310 are printed or otherwise placed on thelabel 304. In the example shown in FIG. 5, the calibration targets 310includes a black patch 316, a contrasting white patch 318, a red patch320, a green patch 322 and a blue patch 324. The label 304 is preferablyformed from a durable material that will withstand normal surgicalinstrument handling, including sterilization by heating or using asterilization chemicals such as gluteraldehyde, which is typically usedto disinfectant endoscope tips. The label 304 may be, for example, aprintable transfer ceramic label available from Dai Nippon.Additionally, calibration targets subject to aging may be imaged underknown conditions and their aged (e.g., faded) calibration values storedin a database.

One method 330 for using the calibration device 300 will now beexplained with reference to the flowchart of FIG. 6. Image properties ofan endoscope system, such as its gain, color balance, sharpness,contrast, etc. are set to initial values in an initialization step 332.The initial values set in step 332 may be factory standard settings,settings determined for particular endoscope system or model ofendoscope system, and/or settings determined from a previous use of theendoscope system, or any combination thereof.

An endoscopic image is then captured at step 334 by video imaging, stillimaging or some other means. After the image is captured at step 334,the image is analyzed at step 336. The analysis step 336 initiallyincludes analysis to determine if the calibration device 300 is presentin the field of view of the endoscope tip. The result of thisdetermination is used at step 338 to determine how next to proceed.

If the calibration device 300 is found not to be present at step 338,the image capture step 334 is repeated. Optionally, when step 338determines that the calibration device 300 is not present in the fieldof view of the endoscope tip, an internal recalibration step 340 may beperformed. This internal recalibration step 340 may include, forexample, adjustment of the gain in the console 120 based on a comparisonof overall or location-specific image brightness of internal bodytissues or organs in the field of view of the endoscope tip. Thus, evenwhen there is no calibration device present in the endoscope tip's fieldof view, circuitry in the console 120 can recognize if the image is toolight or “washed out” and either reduce detector sensitivity, decreaseillumination power output, or modify the image data to reducebrightness. If, on the other hand, the recalibration step 340 determinesthat the image is too dark, circuitry in the console 120 can increasedetector sensitivity, increase illumination power output, or modify theimage data to increase brightness. Methods for providing localcalibration without a calibration device are described in PCT patentapplication No. PCT/US/2004/19996 entitled “Scanning Endoscope,” whichis hereby incorporated by reference.

If the determination is made at step 338 that the calibration device 300is present in the field of view of the endoscope tip, then a calibrationstep 344 is performed. Calibration data is obtained in the calibrationstep 344 by comparing the image of the calibration device captured atstep 334 with calibration device data corresponding to the known opticalproperties of the calibration device 300. The calibration device data isprovided to the console 120 by suitable means. For example, thecalibration device data can be entered into the console 120 using thecontrols 128, and the entered calibration device data are stored in theconsole 120. The calibration device data may also be encoded into thecalibration device 300 itself and read by the console 120 from an imageof the calibration device 300 captured at step 334, or it may beprovided to the console 120 by other means. Regardless of how thecalibration device data is provided to the console 120, the console 120compares the calibration device data to data corresponding to the imagecaptured at step 334. Any differences in such data are indicative ofdeviations of the captured image data from correct image data, and thesedifferences correspond to the calibration data. For example, the imagedata captured at step 334 may result in an image viewed on the monitor126 having a color balance, contrast, brightness, sharpness, etc. thatdoes not match the true color balance, contrast, brightness, sharpness,etc. of the calibration device 300. The calibration data corresponds tothese difference between the captured image data and the calibrationdevice data. Once the calibration data has been obtained by theabove-described or other means, the calibration procedure shown in FIG.6 is complete.

After the calibration data have been obtained, the console 120 uses thecalibration data to either modify the operation of the circuitry in theconsole 120. More specifically, the calibration data can be used toadjust the color balance, contrast, brightness, sharpness, etc. of theendoscope system 10 so that the image displayed on the monitor 126accurately shows the anatomical feature.

Another example of a calibration device 350 is shown in FIG. 7. Thecalibration device 350 includes machine-readable indicia 352 as wellsets 356, 358, 360 and 362 of calibration patches in respective colors.The machine readable indicia 352, which may be used as a “finderpattern” either to determine the presence of the calibration deviceduring analysis at step 336 or to determine the location of calibrationpatches 356-362. Also, as mentioned above, the machine-readable indicia352 may also encode calibration device data indicative of the knownoptical properties of the calibration device 350, such as its centerwavelength, breadth, brightness, calibration patch Lambertiancharacteristics, etc. Alternatively or additionally, a serial numbercorresponding to the calibration device 350 may be encoded in themachine-readable indicia 352. The serial number can then be used toaccess calibration device data indicative of the known opticalproperties of the calibration device 350, which are stored in adatabase. According to some embodiments, the database may be resident inthe console 120. The use of the machine-readable indicia 352 for thispurpose has the advantage of allowing calibration devices themselves tobe re-calibrated if their known optical properties change for variousreasons, such as because of aging, damage or other effects.

With further reference to FIG. 7, the machine readable indicia 352 showntherein includes the data string: [)>[RS]06[GS]YR32G29B30XX[RS]EOT]. Thenon-printable records separator “[RS]” ASCII character indicates whatcharacter will be used to separate messages within the symbol. The “06”indicates the first message in the symbol follows ANSI standard format“06,” which specifies the use of FACT data identifiers to identify datafield contents. The non-printable group separator “[GS]” ASCII characterindicates what character will be used to separate data fields within thefirst (“06”) message string. The first (and only) data identifier “Y”indicates the field is a user-defined data structure. Within that field,“R32” indicates the red patches have absolute reflectance of 32 units,“G29” indicates the green patches have an absolute reflectance of 29units, and the “B30” indicates the blue patches have an absolutereflectance of 30 units, understand the conditions, respectively. The“XX” characters are used to indicate a particular pattern of patches.The next non-printable records separator “[RS]” indicates the end of themessage, and the “[EOT]” non-printable “end-of-text” ASCII characterindicates the end of the structured data. This data structure is simplyone example of a data structure that can be encoded in themachine-readable indicia 352, and other data structures may, of course,be used.

A calibrating device 400 according to another example of the inventionis shown in FIG. 8. The calibrating device includes a cylindrical body404 to which a calibration label 408 is attached. The cylindrical body404 is sized and shaped to pass through a biopsy channel of an endoscopetip (not shown in FIG. 8). The label is printed with indicia 410 havingknown optical properties. The cylindrical body 404 is attached to thedistal end of a catheter 414 through a flex joint 418. A pair of controlcables extend through the catheter 414 and are attached to oppositesurfaces of the body 404.

In operation, the cylindrical body 404 is first inserted into the biopsychannel. The catheter 414 is fed into the biopsy channel until thecylindrical body 404 protects from an opening at the distal end of thechannel. Finally, the control cables are alternately retracted andextended to pivot the cylindrical body 404 within the field of view ofthe endoscope tip.

From the foregoing it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. For example, the teachingsdisclosed herein are generally applicable for use in scanned beamimagers such as bar code scanners in addition to scanned beam endoscopetips. Accordingly, the invention is not limited except as by theappended claims.

1. A method of ensuring that an image of internal anatomical featuresobtained by an endoscope system having an endoscope console and anendoscope tip accurately portrays the anatomical features, wherein theendoscope system includes a biopsy channel extending the length of anendoscope tip from an access port at its proximal end to an opening atits distal end, the method comprising: positioning the endoscope tip sothat the internal anatomical features are within a field of view of theendoscope tip; using the endoscope system to obtain an image of theinternal anatomical features; introducing a calibrating device having atleast one known optical property into the field of view of the endoscopetip, wherein introducing the calibration device comprises: attaching thecalibrating device to a distal end of a catheter; inserting thecalibrating device into the biopsy channel of the endoscope tip; andadvancing the catheter into the biopsy channel of the endoscope tipuntil the calibrating device is within the field of view of theendoscope tip; using the endoscope system to obtain an image of thecalibrating device; providing calibration device data corresponding tothe at least one known optical property of the calibration device; usingthe image of the calibration device and the calibration device data toprovide calibration data; and using the calibration data to program theendoscope system.
 2. The method of claim 1 wherein the act of using thecalibration data to program the endoscope system comprises setting atleast one selected from the group consisting of a gamma curve, agrayscale curve, a gain, a zero point, a color balance and white point.3. The method of claim 1 wherein the endoscope tip comprises an opticalendoscope tip having an optical fiber extending from a viewing window atthe distal end of the endoscope tip to a proximal end of the endoscopetip.
 4. The method of claim 1 wherein the endoscope tip comprises avideo endoscope tip having a video camera mounted behind a viewingwindow at the distal end of the endoscope tip, the endoscope tip furthercomprising wires extending from the video camera to a proximal end ofthe endoscope tip.
 5. The method of claim 1 wherein the endoscope tipcomprises a scanned beam endoscope tip having a beam scanning mechanismmounted behind a viewing window at the distal end of the endoscope tip,the endoscope tip further comprising wires extending from the beamscanning mechanism to a proximal end of the endoscope tip.
 6. The methodof claim 1 wherein the catheter includes at least one control cablestructured to steer the distal end of the catheter in at least onedirection, and wherein the method further comprises manipulating the atleast one control cable to steer the calibrating device to a positionwithin the field of view of the endoscope tip.
 7. The method of claim 1wherein the act of introducing a calibrating device having at least oneknown optical property into the field of view of the endoscope tipcomprises: forming an orifice or incision into a region of a body beingimaged by the endoscope system; mounting the calibrating device to adistal end of an elongated support; and using the support to insert thecalibrating device through the orifice or incision into the region ofthe body being imaged by the endoscope system until the calibratingdevice is within the field of view of the endoscope tip.
 8. The methodof claim 7 wherein the elongated support to which the calibrating deviceis mounted comprises a biopsy or surgical instrument.
 9. The method ofclaim 1 wherein the calibration device comprises: a body portion; and alabel attached to the body portion, the label bearing an indicia havingat least one known optical property.
 10. The method of claim 1 whereinthe act of providing calibration device data comprises: encoding thecalibration device data in the calibration device; and using theendoscope system to read the calibration device data encoded in thecalibration device.
 11. A method of obtaining calibration dataindicative of a calibration error in an endoscope system, wherein theendoscope system includes a biopsy channel extending the length of anendoscope tip from an access port at its proximal end to an opening atits distal end, the method comprising: introducing within a body cavitya calibrating device having at least one known optical property into thefield of view of the endoscope system, wherein introducing thecalibration device comprises: attaching the calibrating device to adistal end of a catheter; inserting the calibrating device into thebiopsy channel of the endoscope tip; and advancing the catheter into thebiopsy channel of the endoscope tip until the calibrating device iswithin the field of view of the endoscope system; using the endoscopesystem to obtain an image of the calibrating device; providingcalibration device data corresponding to the at least one known opticalproperty of the calibration device; and using the image of thecalibration device and the calibration device data to obtain thecalibration data.
 12. The method of claim 11 wherein the endoscopesystem comprises an optical endoscope tip having an optical fiberextending from a viewing window at the distal end of the endoscope tipto a proximal end of the endoscopetip.
 13. The method of claim 11wherein the endoscope system comprises a video endoscope tip having avideo camera mounted behind a viewing window at the distal end of theendoscope tip, the endoscope tip further comprising wires extending fromthe video camera to a proximal end of the endoscope tip.
 14. The methodof claim 11 wherein the endoscope system comprises a scanned beamendoscope tip having a beam scanning mechanism mounted behind a viewingwindow at the distal end of the endoscope tip, the endoscope tip furthercomprising wires extending from the beam scanning mechanism to aproximal end of the endoscope tip.
 15. The method of claim 11 whereinthe catheter includes at least one control cable structured to steer thedistal end of the catheter in at least one direction, and wherein themethod further comprises manipulating the at least one control cable tosteer the calibrating device to a position within the field of view ofthe endoscope system.
 16. The method of claim 11 wherein the act ofintroducing a calibrating device having at least one known opticalproperty into the field of view of the endoscope system comprises:forming an orifice or incision into a region of a body being imaged bythe endoscope system; mounting the calibrating device to a distal end ofan elongated support; and using the support to insert the calibratingdevice through the orifice or incision into the region of the body beingimaged by the endoscope system until the calibrating device is withinthe field of view of the endoscope system.
 17. The method of claim 16wherein the elongated support to which the calibrating device is mountedcomprises a biopsy or surgical instrument.
 18. The method of claim 11wherein the calibration device comprises: a body portion; and a labelattached to the body portion, the label bearing an indicia having atleast one known optical property.
 19. The method of claim 11, furthercomprising storing the obtained calibration device data in the endoscopesystem.
 20. A system for obtaining an accurate image of an internalanatomical feature, comprising: a calibration device having at least oneknown optical property; and an endoscope system, comprising: anendoscope tip having a viewing device structured to provide anelectrical signal indicative of an image of an object image in a fieldof view of the endoscope tip, wherein the endoscope tip includes abiopsy channel extending the length of the endoscope tip from an accessport at its proximal end to an opening at its distal end, and whereinthe calibrating device is structured to be inserted into the biopsychannel, the system further comprising a catheter having a distal end towhich the calibration device is attached; and an endoscope consolecoupled to receive the electrical signal from the endoscope tip, theendoscope console being structured to receive calibration device dataindicative of the at least one known optical property of the calibrationdevice, the endoscope console further being structured to generatecalibration data using the calibration device data and datacorresponding to an image of the calibration device obtained with thecalibration device in the field of view of the endoscope tip, theconsole further being structured to use the calibration data tocalibrate the endoscope system.
 21. The system of claim 20 wherein theendoscope tip comprises an optical endoscope tip having an optical fiberextending from a viewing window at the distal end of the endoscope tipto a proximal end of the endoscope tip.
 22. The system of claim 20wherein the endoscope tip comprises a video endoscope tip having a videocamera mounted behind a viewing window at the distal end of theendoscope tip, the endoscope tip further comprising wires extending fromthe video camera to a proximal end of the endoscope tip.
 23. The systemof claim 20 wherein the endoscope tip comprises a scanned beam endoscopetip having a beam scanning mechanism mounted behind a viewing window atthe distal end of the endoscope tip, the endoscope tip furthercomprising wires extending from the beam scanning mechanism to aproximal end of the endoscope tip.
 24. The system of claim 20 whereinthe catheter comprises at least one control cable structured to steerthe distal end of the catheter in at least one direction.
 25. The systemof claim 20 wherein the calibration device comprises an elongatedsupport and a label attached to the elongated support.
 26. The system ofclaim 25 wherein the elongated support comprises a biopsy or surgicalinstrument.
 27. The system of claim 20 wherein the calibration devicecomprises: a body portion; and a label attached to the body portion, thelabel bearing an indicia having at least one known optical property. 28.The system of claim 20 wherein the calibration device data are encodedin the calibration device.
 29. The system of claim 20 wherein thecalibration device data are programmed in the console.